Heating apparatus.



N. B. WALES HEATING APPARATUS. APPLICATION FILED JAN. 4, i907.

Zflimeaaea: lmvewiw': 7 74, 83 29mm 41 WW 0. "gmxldlmil @9 58}, PatentedNev. 16, 1909.

lilhl sra rns ATET? amen NATHANIEL B. WALES, OF BBAINIREE,MASSACHUSETTS.

HEATING APPARATUS.

Specificationof se uce.

Lett rs P n Patented Nov. 16, 1909.

Application filed January 4:, 1907. Serial No. 350,737;

. and in which the temperature of the fluid is raised to the degreerequired by fir expanding the fluid and then compressing it, heat beingsupplied to the fluid between itsadmission to the expanding mechanismand its admission to the compressing mechanism so that the heating ofthe fluid 1s eifected by doing a comparatively small amount of Workthereon.

It is the object of the invention to provide for so controlling theoperation of the expanding and compressing mechanisms by the pressure inthe system to which the compressed fluid is delivered that the pressuremay be maintained under the varying conditions of use with a minimumexpenditure of power by the mechanism or motor which drives theexpandingand compressing mechanisms. r Y

A further object of the invention is to pro vide for so controlling theexpanding and compressing mechanisms that any desired temperature ortemperatures may be automatically maintained at different points as forinstance in different rooms which are to be heated by the system.

'lfhc various Features of the invention may be embodied in systems inwhich the air or other heat conveying fluid delivered from thecompressing mechanism is discharged di rectly into the rooms or spacesto be heated or in systems in which the air is circulated throughradiators or heating devices and in the latter systems the aircirculated through the radiators or heating devices may or may not bereturned to the ex; inding mechanism to be again circulated through thesystem.

For the purpose of illustration 1 have shown diagrannnatically in theaccompany-- ing drawings an arrangement of apparatus embodying thefeatures my invention.

The various features of the invention will be readily understood fromthe following detailed description of this apparatus and will be moreparticularly set forth in the In the drawingsFigure 1 is a diagrammaticview indicating a heating system constructed and controlled inaccordance with my invention. Figs. 2, 3 and 4 are details of devicesfor varying the amount of compression effected in the apparatus tosatisfy the conditions under which it is being run.

In practicing my invention as shown in the drawings the drivingmechanism for the expanding and compressing mechanisms is controlled bythe pressure in the conduit or system to which the compressed air isdeliv-' cred by the compressing mechanism in such manner as to maintaina substantially constantpressure (that is tosay a pressure which doesnot vary beyond predetermined limits) in the conduit or system.

As shown in the drawings the expanding and compressing mechanisms aredriven by an electric motor and the control'of the expanding andcompressing mechanisms is etfected by controlling the starting andstopping of the motor or controlling the speed of the motor or bycontrolling both the starting and stopping and the speed of the motor.

In the apparatus shown in the drawings the expanding mechanism is inthe-form of a cylinder 1 within which a piston il reciprocates and towhich the air is supplied through a pipe 3. 'lhe supply of air to theopposite sides of the piston is controlled by aniain valve 4 and acut-oil valve 5 which are operated to open and close the supply ports (5at proper intervals The valves are so constructed and operated thatduring the travel of the piston in either direction air will be taken inback of the piston for a portion of its stroke and then the cut-oilvalve will be operated to cut oil the supply of air so that during theremainder of the stroke the air back of the piston will expand. Duringthis stroke of the piston the air in front of the piston which has beenexpanded glun ing the stroke in the opposite directiomwill be deliveredthrough one of the delivery ports 7 which remains open during the entirestroke of the piston. The delivery ports 7 are opened and closed atproper intervals by a valve 8.

The. cylinder 1 may be jacketed as indicated in the drawings and aheating agent may be circulated through the jacket so that the air inexpanding will absorb heat and be delivered from the expanding mechanismat a temperature above that at which it claims.

would otherwise have been delivered.

The expanded air is conducted from the expanding cylinder 1 to acompressing mechanism through pipes 9 and 10 and an interposed series ofpipes 11. During its passage from the expanding to the compressingmechanism heat is supplied to the air and for this purpose the bank ofpipes 11 may be arranged where the temperature of the surrounding air ishigher than the temperature of the expanded air. In case the temperatureof the air as it comes from the expanding mechanism is below thetemperature of the atmosphere, heat may be supplied to the air from theatmosphere as it passes through the bank of pipes. Under some conditionsit may be found desirable and economical to' surround the pipes 11 witha heating agent such as exhaust prodnets of combustion or other wasteproducts containing heat.

The compressing mechanism illustrated consists of a cylinder 12 withinwhich a piston 13 r'eciprocates. The supply of air from the pipe 10 tothe cylinderlQ is controlled through valves 13 and ports 14. During themovement of the piston 13 in one direction air from the-pipe l 0 entersthe cylinder back of the piston during its entire stroke. When thepiston moves in the opposite direction the valve 13 for that end of thepiston closes and the air in front of the piston is compressed until thepressure in front of the piston is sufficient to open the delivery Valve15 for that end of the cylinder when the compressed air is deliveredthrough this valve into the pipe 15 by which it is conducted to theplace where it is to be used for heating purposes. The con'ipressioncylinder may be jacketed if found. desirable and a heating agentcirculated through this jacket from which heat may be absorbed by thecompressed air.

The pistons 2 and 13 are connected by pis- .ton' rods 16 and 17 with thesamecrank 18 in such manner that the expanding stroke of the piston 2occurs during the compression stroke of the piston 13. This reduces thepower required for operating the mechanism since the expansion of theair in the expanding mechanism tends to drive the piston of thecompressing mechanism during its compression stroke.

The crank 18 is connected with a driving shaft 19 and the compressingand expanding mechanisms are driven by an electric motor 20 connectedwith the driving shaft 1.) through suitable earing indicated at 21.

In order thatthe apparatus may be regulated or adjusted to vary theamount of compression to suit the varying conditions under which theapparatus may be used, means are provided for regulating the cutting of?of the supply of air to the expansioncylinder. By this means the amountof expansion is varied and consequentlythe. amount of compressionrequired in the compressing mechanism to compress the air to a givenpressure. The temperature range through which the air is raisedtherefore may be varied in accordance with the temperature conditions ofthe atmosphere at the time of use and according to the temperature towhich it is desired to raise the air in the apparatus.

The devices indicated in the drawings for operating the valves andvarying the cut off are as follows. The main supply valve 4 as well asthe exhaust valve 8 of the expansion cylinder, are shifted at each endof the stroke of the piston 2 by means of tappet arms 22 secured to thepiston rod 16 an: ar ranged to alternately engage collars 23 se-' curedto the valve rods 24. The cut-off valve 5 is operated by an eccentric 26connected with the valve by an eccentric strip and rod 27. The eccentricis loosely mounted on the crank shaft 15) between collars 28. Theeccentric is connected to revolve with the shaft by means of a lug 29formed on the end of a rod 30 which is mounted within the shaft 19. Thelug projects radially through aslot bl in the shaftand engages a spiralgroove 32 formed in the bore of the eccentric. So long as the rod 30remains in a fixed position longitudinally of the shaft the eccentricwill remain in fixed relation to the shaft, thus operating the cut-offvalve to cut off the supply of air to the expansion cylinder at adefinite point in the stroke of the piston. If the rod 30 is shiftedlongitudinally of the shaft the lug 2f) working in the spiral groove 32will shift the eccentric about the shaft thus varying the point of cutoil". The rod 30 projects beyond the end of the shaft 19 and connectedby means of collars 33 and pin 34 with one end of a lever 35. The lever35 is connected by means of an adjustable link 36 with a fixed pivot 37so that by adjusting the lengtl'i of the link 36 the position of the rod30 longitudinally of the shaft may be varied, thus varying the positionof the eccentric and the cutofl' of the expanding cylinder.

In the apparatus or system shown in the drawings the conduit or pipe 15to which the compressed air is delivered by the compressing mechanism isconnected by branch pipes 38 with a series of radiators 3i) indicated asarranged in different rooms and in turn connected through pipes 40 witha return pipe 41 which communicates with the intake pipe 3 of theexpansion cylinder through a valve 42. The delivery of air through theheating devices 3) to the discharge pipes 40 is controlled by valves 43the openmg and closing of which may be effected manually or may beautomatically controlled by thermostats 14 as indicatet So long as allof the valves 43 which control the delivery of air from the pipe 15remain closed there will be no discharge of air "pipe through thecorresponding radiator 9. and into the return pipe 41. If asubstantiallyconstant pressure is to be maintained in the pipe 15 or inthe system the expanding and compressing mechanism should thereforeremain out of action so long as all of the valves 43 remain closedbutfshould be started into action when any one'o'f the valves is open inorder to supply hot air to the pipe 15 and to the radiator correspondingto the open valve or valves.

In case only a few radiators or heating devices are to be supplied fromthe conduit 15 a substantially constant pressure might'be effectivelymaintained by thus throwing the expanding and compressing mechanism inand out of action, the mechanisms being thrown into action whenever thepressure within the pipe 15 fell by reason of the opening of-oneor moreof the valves and the mechanisms being thrown out of action whensuflicient compressed heated air had been supplied to the pipe 15 tosupply the air delivered through the open valves and to restore thepressure in the pipe 15 to normal, In case however there are a largenumberof radiators or heating devices supplied .firom the pipe 15 thenthe pressure within the system may be more effectively and economicallymaintained by varying the speed of the expanding and compressing fmechanisms in suchmanner that these mechanisms will be started at a slowspeed sumcient to Supply the quantity of air which wouljd be deliveredfrom the pipe 15 in case one or two valves 43 were open and the speedwill be increased should the pressure in the pipe 15 continue to fall byreason of an insufiicient supply of air to the pipe 15 or by reason ofthe opening of an increasing number of the valves.

In systems in which there is a constant delivery of air from the conduitto which the compressed air is delivered but in which the quantityrequired to be delivered may Va a constant pressure may be maintainedwithin the conduit by varying the speed of the expanding and compressingmechanisms and insuch case the throwing of the expending and compressingmechanisms into and out/ 015 action automatically may be omitted.

i In the construction shown in the drawings the operation of theexpanding and compressing mechanisms is controlled by bothautomaticallythrowing these mechanisms into'and out of action and automatic all-yvarying the speed of their operation so that the expanding andcompressing mechl HILLSms are thrown into operation whenever thepressure in the conduit or systen'i falls by reason oi the opening ofone or more o F the valves through which air is delivered from theconduit, the speed of operation of the expanding and compressingmechanisms being varied according to the number oi valves which areopen. The throwing of the expanding and compressing mechanisms into andout of action is effected by a starting and Stopping mechanism whichcontrols the starting and stopning of the electric motor 20 which drivesthose mechanisms. This starting and stopping mechanism may be oi anysuitable construction and one form oi such mechanism is indicated in thedraw ings. of the motor is effected through a switch 45 which opens andcloses the circuit through the coil of a solenoid 16. The current issupplied to the solenoid circuit from the feed wires 4-? of the motorthrough shunt wires d8 and resistance 49 connected to the pivot of theswitch. VVhcu the circuit is closed by the switch d5 the solenoid 16operates an arm 50 of a switch which completes the connection betweenthe motor and the feed wires through a rhcostat 51 in a well knownmanner.

The opening and closing of the switch 45 is controlled by the pressurewithin the con duit 15 through a diaphragm (not shown) arranged withinthe casing 52 and subjected upon its under side to the pressure withinthe pipe 15 through a pipe leading from the pipe 15 to a chamber formedwithin the casing 52 beneath the diaphragm. The diaphragm is connectedby a pin or plunge 5d with a lever 55 pivoted to the casing 52 andconnected at its free end with the switch 15 through a link The levercarries a weight 57 which may be adjusted to counterbalance any givenpressure upon the under side of the diaphragm within the casing 52 and.consequently to couutcrbalance any given pressure within the pipe 15.

By these devices just described the starting and stopping of the motorand ofthe expanding and compressing mechanisms is controlled by thepressure within the con duit 15 and within the system. If the pressurewithin the pipe 15 falls by reason of the opening of one or more of thevalves 43 the pressure on the diaphragm within the easing 52 falls sothat the lever 55 swings downward thus operating the switch 45 to closethe solenoid circuit and to cause the starting of the motor. When thepressure within the pipe 15 is restored the pressure on the diaphragmwithin the casing 52 swings the ever 55 upward .thus operating theswitch '45 to open the solenoid circuit and thus stop the motor.-

in the construction shown the variation in the speed of operation of theexpanding and compressing mechanisms is effected by As shown thestarting and stopping varying the speed of the motor and any suitableform of speed "changing devices may be employed for this pur ose. Oneform of such speed changing mec anism is indicated in the drawings inwhich 58 indicates a resistance included in the circuit through whichthe field magnets are excited and whic may be varied in any well knownmanner to vary the speed of the motor. The speed of the motor andconsequently of the expanding and compressing mechanisms is controlledby the pressure within the pipe 15 and system by means of a diaphragm(not shown) arranged above a chamber formed in a casing 59. The chamberbelow the diaphragm is connected through a pi e 60 with the pipe 53which leads from the conduit 15 to thecasing 52 heretofore re ferred to.The diaphragm within the casing 59 is connected by a pin 61 with thelever 62 pivoted to the casing and connected at its free end with acontact 63 by the movement of which the resistance 58 is varied. The

lever 61 is held against'the pressure exerted on the under side of thediaphragm by means of a spring 64 the tension of whichmay be adjusted bya screw 65.

When the expanding and compressing mechanisms are started into actionthey are driven at a comparatively slow s eed which should be sufiicientto maintain t 1e pressure within the conduit and system when only asmall proportion of the valves 43 are open. If the pressure Within theconduit and system continues to fall the supporting pressure upon thediaphragm within the casing 59 diminishes and the lever 62 is moved tooperate the contact 63 and thus vary the re sistance 58 to increase" thespeed of the motor and of the expanding and compressing mechanisms. Thisincrease in speed will continue until the mechanisms are being driven attheir full capacity or until the pressure in the system is maintained.Should the pressure within the system rise the speed of the motor andexpanding and compressing mechanisms will be decreased until the minimumspeed is reached. This speed will continue so long as it is suihcient tomainlain the pressure in the system. If the pressure in the system risesuntil it over-balances the pressure exerted on the diaphragm within thecasin 52 by the weight 57 then the switch 45 will be operated to stopthe motor and the expanding and compressing mechanisms.

In case the valves 43 are controlled by thermostats any desiredtemperature may be automatically maintained in each of the re nns andthe apparatus be automatically controlled to economically suppl theamount of air required according to the number pf valves which are open.

In case the air which is deliyered from the conduit 15 is returned tothe expanding state? mechanism after passing through the heating devicesto be again passed through the system, it is desirable that some meansbe provided for supplying fresh air to the system to compensate for anyleakage or loss which may occur. Any suitable form of devices foreifecting this purpose may be employed and one form of such device whichis automatically controlled to supply fresh air to the system wheneverby reason of leakage or loss the pressure within the system falls belowa predetermined point, is shown in the drawings. This device comprises acylinder 66 within which reciprocates a piston 67. The upper end of thecylinder is connected by means of a pipe 68 with the conduit 15 whichleads from the compressing mechanism to the 'heat using devices of thesystem. The lower end of the cylinder communicates through an intakevalve 69 with the atmosphere and communicates through a delivery valve70 with apipe 71 which leads from the conduit 15. The pipe 71 isprovided with a valve 72 which serves to open and close communicationbetween the end of the cylinder and the conduit 15. The piston 67 isconnected with a piston rod 73 the upper end of which is arran 'ed tqbeacted upon by a cam 74 secured to the shalft 19.

By reason of the fact that the piston rod 73 is connected to the underside of the piston 67 the effective area of the upper side of" thepiston is greater than the eifective area of the under side of thepiston and a given pressure below the piston will .therefore git-use theair above the piston to be compressed to a higher pressure. Assumingthat the valve 72 is open the operation of the device will be asfollows. on the up stroke of the piston air will be drawn in through thevalve (39, the valve 70 being held closed by I the pressure within thesystem. As the cam 7 4 releases the piston the pressure on the upperside of the piston will force it downward, the valve (59 closing toprevent the escape of air from below the piston. The air below thepiston will thereforebe compressed until the pressure is greater thanthe pressure within the system when the valve 70 will open and the airbelow the piston be forced into the system through the pipe 71. On-thenext up stroke of the piston the valve 70 will close and the valve 69will open to allow a fresh supply of air to enter the lower end of thecylinder below the piston when the operation will be repeated. Thus solong, as the valve 72 remains open the pump will operate to supply airto the system and to build up the pressure therein. When the valve isclosed the piston 67 will be forced upward to the upper end of itsstroke each time the cam 74 revolves and when released by the cam willreturn .until the ressure within the lower end of the cylin er and thecompressing mechanism.

pipe Tl balances the pressure above the piston when the piston willremain at rest until again depressed by the cam.

The device for opening the valve 72 and thus throwing the compressingdevice operation when the pressure within the ten; below a certainamount compresses a casing T which is connected by means of a pipe T8with the conduit 15 leading from casing i5 isa diaphragm (not shown)which is connected by means of a linl; T7 with a lever 75. The lever, isconnected-by means of a llnez 79 with an operating arm 80 which isconnected with the valve 72. An adjustable weight 81 is mounted upon thelever 78 and tins weight may he ad uStcd to regulate the pressurerequired to operate the diaphragm and through it to operate theugust-111g the apparatus lor any 911K811 "tween the lower end of thecylinder 66 and the conduit 15. Air will now he forced into the systemuntil the pressure in the conduit 15 is restoredwhen the lever 78 willheraised to close the valve 72. Thus the requisite quantity of air will beautomatically maintained in the system and fresh. air supplied tocompensate for any leakage.

In startin "the system in the first instance after it has een' adjustedto suit the conditions under which it is to he used and after the valves15 have been adjusted for the "pressure which it is desired to maintainin the conduit 15 and system the valveAlZ is closed and a valve 82 isopen. The valve 82 is mounted in a pipe 83 which leads from theatmosphere to the intake pipe 3 of the expansion cylinder. Whenthe valve82 is open therefore and the valve d2'closed the intake pipe of theexpansion cylinder is in communication with the atmosphereand 13 cut'ofi from communication with the return pipe 41 of the system. Theexpanding and compressing mechanisms are'now run until the desiredressure' is secured in the conduit 15 and in t e system and then thevalve 82 is closed and the valve 42 bpen. 1

It will he understood that the construction of the expanding andcompressing mechanisms and of the various other devices and ease? into.

Within the I nations the weight 81 is so adjusted that mechanisms shownin the drawings are shown For the purpose of illustration merely andthat the illustration to a greatextent diagrammatic.

the various constructions and arrangements in which the features of theinvention may he embodied, what i claim and desire to se cure by LettersPatent is z- 1. A heating apparatus comprising a' fluid expandingmechanism, a fiuid compressing mechanism, means for supplying heat tothe laid between its admission to the expanding mechanism and itsadmission to the compressing mechanism, mechanism for driving saidexpanding and compressing mechanisms, a conduit to which the fluid isdeliv cred from the compressing mechanism and from which. it isdeliveredto the expanding mechanism, and devices "for controlling thedriving mechanism by the pressure in the conduit,

ii heating apparatus comprising a fluid expanding mccl'i...s1n, a iiuidcompre. in mechanism, means for supplying heat to the fluid between itsadmission to the expanding mechanism and its admission to thecompressing mechzniiszn, mechanism for driving said expanding andcompressing mechanisms, a conduit to which the fluid is deliv-.

cred from the compressing mechanism provided with a plurality ofdelivery cutlets, valves for controlling said outlets, and devices forcontrolling the driving mechanism by the pressure in the conduit..

3. A heating apparatus comprising a fluid expanding mechanism, a fluidcompressing li ithout attempting to point out in detail mechanism, meansfor supplying heat to the fluid between its admission to the expandingmechanism and its admission to the compressing mechanism, mechanism fordriv' g said expanding and compressing inecham isms, a conduit providedwith a plurality of delivery outlets, valves for controllingsaidoutlets, a separate thermostat for controlling each valve, and devices.for controlling the driving mechanism by the pressure the conduit.

i. A heating apparatus comprising a fluid expanding mechanism,'a fluidcompressing mechanism, means for supplying heat to the fluid between itsadmission to the expanding mechanism and its admission tothe comressingmechanism, a conduit to which the Said is delivered from the compressingmechanism, mechanism for varying the speed of the expanding andcompressing mechanisms controlled by the pressure in the conduit.

5. A heating apparatus comprising a fluid expanding mechanism, a fluidcompressing mechanism, means for supplying heat to the fluidbetween itsadmission to the expanding mechanism and its admission to thecompressing mechanism, a conduit towhich the fluid is delivered from thecompressing meching the expanding and compressing mechanisms into andout of operation controlled by the pressure in the conduit.

6. A heating apparatus comprising a fluid expanding mechanism, a fluidcompressing mechanism, means for supplying heat to the fluid between itsadmissiqn to the expanding mechanism and its admission to the compressinmechanism, a conduit to which the fluid isflelivered from thecompressing mechanism pro ided with a plurality of delivery .outlets, vaves for controlling said outlets, and mechanism for varying the speed ofthe expanding and compressing mechanisms in accordance with the numberof valves open.

7. A heating apparatus comprising a fluid expanding mechanism, a fluidcompressing mechanism, means for supplying heat to the fluid between itsadmission to the expanding mechanism and its admission to the compressinmechanism, a conduit to which the fluid is elivered from the compressingmech anism provided with a plurality of delivery outlets, valves forcontrolling said outlets, a thermostat for/controlling each valve, and

mechanism for varying the speed of the expanding and compressingmechanisms in accordance 'with the number of valves open.

8. A heating apparatus comprising a fluid expanding mechanism, a fluidcompressing mechanism, means for supplying heat to the fluid between itsadmission to the expanding mechanism and its admission to thecompressing mechanism, mechanism for drivlng said expanding and compressng mechan sms, a conduit to which the fluid is delivered from thecompressing mechanism rovided with a plurality of delivery outets,valves for controlling said outlets, and mechanism controlling thedriving mechanism to maintain a substantially constant pressure in theconduit.

9. A heating apparatus comprising a fluid expanding mechanism, a fluidcompressing mechanism, means for supplying heat to the fluid between itsadmission to the expanding mechanism and its admission to thecompressing mechanism, mechanism for driving said expanding andcompressing mechanisms, a conduit to which the fluid is delivercd fromthe compressing mechanism provided with a plurality of delivery outlets,valves for controlling said outlets, a separate thermostat forcontrolling each valve, and mechanism controlling the driving mechanismto maintain a substantially constant pressure in the conduit.

10. A heating apparatus comprising a I I s b fluid expanding mechanism,a fluid compressing mechanism, means for supplying heat to the fluidbetween its admission to the expanding mechanism and lts admission tothe compresslng mechanism, mechanism for driving said expanding andcompressing mechanisms, a conduit to which the fluid is delivered fromthe compressing mechanism provided with a plurality of delivery outlets.valves for controlling said outlets, and devices for throwing thedriving mechanism into and out of operation and for varying the speed ofthe driving mechanism controlled by the pressure in the conduit.

11. A heating apparatus comprising a fluid expanding mechanism. a fluidcompressing mechanism, means for supplying heat to the fluid between itsadmission to the expanding mechanism and its admission to thecompressing mechanism, mechanism for driving said expanding andcompressing mechanisms, a conduit to which the fluid is delivered fromthe compressing mechanism provided with a plurality of delivery outlets,valves for controlling said outlets, a thermostat for controlling eachvalve, and devices for throwing the driving mechanism into and out ofoperation and for vary ing the speed thereof controlled by the pressurein the conduit.

12. A heating apparatus comprising afluid expanding mechanism, a fluidcompressing mechanism, means for supplying heat to the fluid between itsadmission to the expanding mechanism and its admission to thecompressing mechanism, mechanism for driving said expanding andcompressing mechanism, a conduit to which the fluid is delivered fromthe compressing mechanism and from which it is delivered to theexpanding mechanism, devices for supplying fresh fluid to the conduit tocompensate for leakage, and devices for controlling the drivingmechanism by the pressure in the conduit.

13. A heating apparatus comprising a fluid expanding mechanism, a fluidcompressing mechanism, means for supplying heat to the fluid between itsadmission to the expanding mechanism and its admission to thecompressing mechanism, mechanism for driving said expanding andcompressing mechanisms, devices acting to automatically supply freshfluid to.the system when the pressure in the conduit falls below apredetermined point, and devices for rontrolling the driving mechanismby the pressure in the conduit.

14. A heating apparatus comprising a fluid expanding mechanism, a fluidcompressing mechanism, means for supplying heat to the fluid between itstldll'llSSlOll to the expanding mechanism and its admission to thecompressing mechanism, mechanism for driving said expanding andcompressing mechanism, a conduit to which the fluid is delivered fromthe compressing mechanism provided with a plurality of delivery outlets,devices acting to automatically supply fresh' fluid to the system whenthe pressure in the conduit falls below a predetermined point, anddevices for coni'i'olling the driving nmclmnism by the pressure in theconduia'. I

15. A hunting zq'ipnrzitns comprising a fluid expanding mechanism, afluid c0mpressingmechanism, means for supplying heat to the fluidbetween its admissibn t0 the expanding mechanism and its admission tothe COHIPIBS iDg mechanism, :1v conduit to which finidis deliwgi-ed fromthe compress- 1 ing mechanism and from which it is deiiw ered to theexpanding mechanism, and mech- :iniszn for varying the speed 01'? theexpand- I ing and c0111pressii'lg mechanism controlled I by the pressurein the conduit. In witness whereof I my hand, this 2nd day of January1907.

NATE ANIEL 3. WALE S. In the presence of IRA L. FISH, KATHARINE A.DUGAN.

have hereunto set

